Your commission wasn’t taxed at 40%. That figure is what the combined withholdings add up to on a commission check: a flat 22% for federal income tax on supplemental wages, 7.65% for Social Security and Medicare, and another 3% to 11% for state and sometimes local income tax. Stack those together and the deduction on a commission check often lands in the 35% to 42% range. None of it is your final tax bill. It’s a prepayment, and commission earners routinely get a chunk of it back at tax time.
Commissions Are Treated as Supplemental Wages
The IRS classifies commissions, bonuses, and overtime as supplemental wages: pay on top of your regular salary or hourly rate. Because these payments are irregular, payroll can’t apply your normal W-4 math to them. Your regular paycheck withholding is calibrated to your entries and spread evenly across pay periods. A big commission check breaks that balance, so the IRS gives employers a separate set of rules for handling the tax.
Those rules leave employers two options. Most pick the simpler one: withhold a flat 22% for federal income tax. The alternative, called the aggregate method, is more complicated and often results in even higher withholding. Either way, your commission gets treated differently from your salary, which is why the deduction feels so steep.
The 22% Federal Flat Rate
For supplemental wages totaling $1 million or less during the calendar year, employers can withhold federal income tax at a flat 22%. No adjustments for filing status, no consideration of your W-4 entries. The IRS sets this rate in Publication 15 as a simplified approach that works for most commission earners.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
If your total supplemental wages for the year exceed $1 million, the rate on the amount above that threshold jumps to 37%, matching the top federal bracket. That mandatory rate applies regardless of what your W-4 says.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
How 22% Compares to Your Actual Tax Bracket
For 2026, federal income tax brackets range from 10% on the first $12,400 of taxable income for a single filer up to 37% on income above $640,600.2Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill The 22% flat withholding rate lines up with the bracket that starts at $50,400 for singles and $100,800 for married couples filing jointly. If most of your taxable income sits in the 10% or 12% bracket, the 22% withholding overshoots your actual liability, and you’ll likely get a refund. If you’re already in the 24% or 32% bracket, 22% slightly under-withholds on the federal side, though FICA and state taxes usually cover the gap.
The Aggregate Method Is Why Some Checks Look Even Worse
Some employers skip the flat 22% and use what the IRS calls the aggregate method. The payroll system adds your commission to your regular wages for that pay period, then withholds as if you earned that combined amount every pay period for the year. A $10,000 commission on top of a $3,000 biweekly paycheck makes the system treat you as if you earn $13,000 every two weeks, or roughly $338,000 annually, pushing that check’s withholding into the 32% or 35% bracket.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
That’s the reason some commission checks look worse than the 40% most people complain about. The system isn’t wrong; it’s making a bad assumption about your annual income based on one pay period. Over-withholding under this method tends to be larger, but so does the eventual refund. Your payroll department can tell you which method they use. If they use the aggregate method and you’d prefer the flat 22%, some employers will accommodate that request.
FICA Sits On Top of All of That
Every dollar of commission is also subject to Social Security and Medicare taxes under the Federal Insurance Contributions Act. Social Security takes 6.2% and Medicare takes 1.45%, combining to 7.65%.3Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates The rates are the same whether the money is salary or a commission check. There’s no special supplemental rate for FICA.
This 7.65% is the piece that pushes total withholding from the 22% federal range into the 30% range before state taxes enter the picture. Unlike federal income tax, where the withholding is an estimate trued up on your return, FICA is essentially final. You won’t get Social Security or Medicare withholding back as a refund in ordinary circumstances.
Two exceptions matter if you’re a high earner. Social Security tax only applies to the first $184,500 of earnings in 2026, so once your combined salary and commissions cross that line, the 6.2% piece stops for the rest of the year.4Social Security Administration. 2026 Cost-of-Living Adjustment (COLA) Fact Sheet Going the other direction, an extra 0.9% Additional Medicare Tax kicks in once your wages exceed $200,000 in a calendar year, taking Medicare from 1.45% to 2.35% on the amount above that line.5Internal Revenue Service. Topic No. 560, Additional Medicare Tax
State and Local Income Tax
Nine states have no income tax at all, so commission earners there skip this layer. For everyone else, state withholding adds another slice. Many states apply their own flat supplemental rate to commissions, similar to the federal 22%. Others require employers to use the state’s regular progressive tables on the combined pay period income. Rates vary widely, from under 2% in some states to above 10% in the highest-tax jurisdictions. Some cities and counties add local income taxes on top.
Combine a 5% state rate and a 1% local tax with the federal 22% and FICA’s 7.65% and you’re already at 35.65% before any other deductions. In higher-tax areas, that total crosses 40% easily. This layering is the core reason your commission check feels like it lost nearly half its value.
Where the 40% Actually Comes From
A realistic breakdown for a commission earner in a moderate-tax state:
- Federal income tax at the flat supplemental rate: 22%
- Social Security: 6.2%
- Medicare: 1.45%
- State income tax (varies by state): around 5%
- Local income tax where applicable: about 1%
That totals 35.65% in a moderate-tax location. Push the state rate to 8% or add heavier local taxes and you’re at 38% to 42%. If your employer uses the aggregate method instead of the flat 22%, the federal portion alone can hit 30% or higher, easily pushing the combined deduction past 40%. The math stops looking mysterious once you see each layer separately, but payroll systems rarely break it down that clearly on a pay stub.
Withholding Is Not Your Final Tax Bill
Forty percent withheld does not mean 40% owed. Withholding is a forced prepayment system. The government collects estimated taxes as you earn, and your actual liability is only settled when you file Form 1040. At that point, all your income is combined, deductions are applied, and your real effective rate emerges.
For 2026, the standard deduction is $16,100 for single filers and $32,200 for married couples filing jointly.2Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill Those deductions reduce your taxable income before the rates apply. Credits reduce your bill further; the Child Tax Credit is worth up to $2,200 per qualifying child and offsets your tax dollar for dollar. If your employer withheld more than you ultimately owe, the IRS sends the difference back as a refund.
For a lot of commission earners, the flat 22% federal withholding overshoots their actual effective federal rate. Someone earning $75,000 in total income with a $16,100 standard deduction has taxable income of $58,900 and an effective federal rate closer to 13%. The 22% withheld on their commissions was too high, and the difference comes back in April. The withholding system is deliberately designed to over-collect slightly rather than risk under-collection, which is why commission checks consistently feel overtaxed.
How to Keep More of Each Commission Check
You don’t have to accept the over-withholding and wait for a refund. A few adjustments can put more money in your pocket during the year instead of giving the government an interest-free loan.
Start with the IRS Tax Withholding Estimator at irs.gov/W4App. It calculates how much federal tax you should have withheld based on your actual income, deductions, and credits, and it accounts for supplemental income.6Internal Revenue Service. Tax Withholding Estimator FAQs Run it after a large commission to see whether an adjustment makes sense.
Then update your Form W-4. Two fields do the work for commission earners.7Internal Revenue Service. Form W-4 (2026) Employee’s Withholding Certificate Step 4(b) lets you enter deductions above the standard amount, which reduces per-paycheck withholding and shrinks a bloated year-end refund. Step 4(c) lets you request an extra flat dollar amount withheld from each paycheck if your commissions are large and unpredictable and you’d rather build a safety cushion than owe in April. You can submit a new W-4 to your employer at any time, as often as you want. If your commissions are seasonal, adjusting at least twice a year makes sense: once after your biggest commission period and once near year-end when total income comes into focus.
Watch the Underpayment Penalty
Cut your withholding too aggressively and you could owe a penalty for underpaying during the year. The IRS expects prepayment as you earn, not one lump sum in April. You avoid the underpayment penalty if you owe less than $1,000 when you file, or if you’ve paid at least 90% of your current year’s tax or 100% of last year’s tax through withholding and estimated payments.8Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
One catch for higher earners: if your adjusted gross income exceeded $150,000 in the prior year, or $75,000 if married filing separately, the safe harbor requires 110% of last year’s tax rather than 100%. Commission earners with volatile income should watch this. If your commissions swing hard from one year to the next, the prior-year safe harbor can be either your best friend or an expensive trap. The Withholding Estimator is the fastest way to check whether you’re on track.